The UI in Rowland's demo at 32min is feeling a little DearImGui / Reaper-ish, kinda bland while also being non-native. But I've seen all the UIs that Arturia & everyone else makes with JUCE, even what Valhalla does with it with their NASA inspired interfaces, so it can clearly make amazing stuff.
I can't believe we're now looking to PACE of all companies to help indie devs. I hated iLok for so long even though I have two iLok dongles now ;)
Which, I hope, you do.
(PS; - the default UI skin is, imho, intentionally a tad bland in order to promote developer uptake of JUCE' pretty amazing skinning/UIBehaviour system...)